The present invention relates to a corrugated shipping container having an integral plastic bag. The container is formed so that the bag does not have to be inserted separately when the box is set up for use. While not in any way so limited, the container is particularly useful for products such as moist fresh vegetables that are loaded in the field and then are subject to a vacuum cooling step.
The miracle of modern transportation and storage systems has made fresh fruit and produce of the highest quality available year round. Even delicate off-season produce such as strawberries and raspberries find their way from growers in South America to tables in the United States and Canada while still in prime condition. Apples and pears are crisp and juicy six to nine months after they were picked thanks to controlled atmosphere cold storage in which oxygen level is reduced and carbon dioxide is increased. Highly perishable products are fumigated periodically with sulfur dioxide during storage to prevent deterioration due to botrytis growth. Field crops, such as celery and broccoli, may be stored for several days before they are shipped to market. If the latter two crops may be used as examples, a critical part of maintaining them in good condition is rapid chilling as soon as possible after harvest. The temperature may be brought down in chillers adjacent the growing fields. Sometimes crushed ice is applied to the produce in the container to maintain the quality. When ice is used, this requires a waxed container or one otherwise made water resistant, such as the one described in U.S. Pat. No. 6,338,234.
One method of cooling involves field packing the produce in a shipping container lined with a separate plastic bag. Liquid water is added, the amount depending on the ambient temperature of the produce when packed. A free end of the plastic bag is then tucked in over the produce providing a loose closure. Thereafter the package is palletized and inserted into a vacuum chamber where the produce temperature is rapidly reduced to its desired level for storage and shipping. A process of this type is described in detail in U.S. Pat. Nos. 5,421,138 and 5,619,841.
Some problems have arisen in conjunction with the above described procedure. One is that it generally requires one worker doing nothing but inserting the plastic bags into the boxes for use by the pickers. Another problem relates to the endemic windy conditions in the growing fields. It is quite common for the bags to blow out of the boxes before the produce is added necessitating a new bag to be supplied. An additional problem is the telescoping of the bag into the box as it is filled leaving an inadequate amount of the top portion of the bag for the required closure.
The container of the present invention has addressed all of the above problems and now provides a solution.
The present invention is directed to a corrugated shipping container containing an integral plastic bag and to the method of its formation. The method requires providing a supply of flat container blanks. These blanks will have the usual face panels and end panels defining the sides of the container and most usually a narrow panel at one end to provide a manufacturers joint when the box is formed. The blanks will also have the usual top and bottom closure flaps that may be any of several commonly used designs. The terms xe2x80x9cface panelxe2x80x9d and xe2x80x9cend panelxe2x80x9d are used based on the usual box design that is rectangular in cross section. If the ultimate box is of square cross section one set of panels may be arbitrarily assigned as xe2x80x9cface panelsxe2x80x9d and the other set as xe2x80x9cend panelsxe2x80x9d. The usual top to bottom score lines will be present between the face and end panels. In addition, a so-called top-to-bottom xe2x80x9cblindxe2x80x9d score line will be placed down the center of each of the end panels and adjacent flaps. The critical function of these blind score lines will be described later.
In the usual method of preparation, the blanks will be fed from a stack onto a conveyor. Adhesive will be appropriately applied to the blanks in the desired areas of the face and end panels. The preferred area for adhesive application is along or adjacent to the score lines separating the face and end panels. Optionally, adhesive may also be applied at this time to the area of the narrow panel forming the manufacturers joint. Normally no adhesive will be applied to the flaps at this time. However, an optional small spot of adhesive; e.g., about 1 cm or less in diameter, may be used in the interior center of each flap to assist in opening the bag when the box is erected. The bottom flaps may then be glued or otherwise closed when the box is ultimately set up to receive its contents.
Plastic bags will be fed from a roll and laid down on the blanks as they advance down the conveyor line. Each bag will be longer than the distance from the outer edges of the top to bottom flaps by the amount the plastic bag is to extend from the top of the set up container. Similarly, each container blank will be spaced apart from its adjacent blank on the conveyor a distance similar to that just noted. This provides a sufficient length at the open top of the bag to form the ultimate loose closure. The bags are typically supplied end-to-end from the roll attached to each other. They will have a heat sealed closure at one and a perforated tear line at the open end, similar to the produce bags commonly supplied in grocery stores. Preferably the leading end will be the heat-sealed end. However, it should be considered to be within the scope of the invention to use the opposite arrangement; i.e., the heat-sealed end trailing. Whether leading or trailing, the heat-sealed end will be laid down roughly adjacent the outer edge of the lower flaps. Down the line the blanks with the now attached bags can be accelerated to separate the bag units along the transverse perforations.
As a final step in the process, the container blanks are now folded over upon themselves along each of the blind score lines. This brings the adhesive into contact with both sides of the plastic bag. It is convenient also to glue the manufacturer""s joint at this time. The still flat containers may then be stacked for storage and shipping.
Either flat or gusseted plastic bags may be used. If flat bags are used, they will be placed on the container blank with their edges lying along the blind score lines. When gusseted bags are chosen, they will be placed on the container blank with their edges lying along the score lines defining one of the face panels. With gusseted bags, the width of the face portion should be essentially equal to the interior edge-to-edge length of the face panels of the container blank. Similarly, the extended width of the gusseted portion should be essentially equal to the interior edge-to-edge width of the end panels of the container blank. If flat bags are chosen, the combined width of both sides should be essentially equal to the inner perimeter of the container.
When the container is ultimately erected for use the end panels, which were initially folded along the blind score lines, will be extended as normal flat panels. The initial folding along the blind score lines makes box set up convenient and easy.
It is a principal object of the invention to provide a corrugated shipping container with an integral plastic bag, the container being especially useful for shipping moist products.
It is another object to provide a method of forming the above container.